You need to sign up for Google AdSense account and then you get your Google ID. After that you copy and paste it into AFFILIATE SETTINGS when you go into your account here on Hubpages. Once you have done that, whenever someone clicks on a Google ad on your hub you will share revenue with Hubpages. It is a slow process, to earn money this way, but it works. And why not, Google ads are there anyway, whether you are in the affiliate programe or not. Just one warning, never click on your own ads because google will figure that out and cancel your account.